What Is Glaucoma? Types and Risk Factors

Glaucoma is not a single disease. Several distinct types exist, each with different causes, progression patterns, and treatment approaches.

Open-angle glaucoma is the most common form, accounting for roughly 90 percent of all cases. In this type, the drainage angle where the iris meets the cornea remains physically open, but the trabecular meshwork (the eye's internal drain) becomes less efficient over time. Pressure rises gradually, and vision loss develops so slowly that most people have no symptoms until the disease is moderately advanced. Regular comprehensive eye exams are the only reliable way to catch it early.

Angle-closure glaucoma occurs when the iris bows forward and physically blocks the drainage angle. An acute angle-closure attack causes a sudden, dramatic spike in eye pressure and is a medical emergency. Symptoms can include severe eye pain, headache, nausea, blurred vision, and halos around lights. Chronic angle-closure develops more slowly but still requires prompt treatment to prevent optic nerve damage.

In normal-tension glaucoma, optic nerve damage occurs even though intraocular pressure measurements fall within the statistically normal range (typically 10 to 21 mmHg). Researchers believe that reduced blood flow to the optic nerve, structural vulnerability, or other vascular factors may play a role. This type is more common in people of Japanese descent and in those with a history of migraines or low blood pressure.

Secondary glaucoma develops as a result of another eye condition, injury, or medication. Causes include eye trauma, inflammation (uveitis), advanced cataracts, certain steroid medications, and prior eye surgery. Pigmentary glaucoma and pseudoexfoliation glaucoma are two specific secondary forms that occur when microscopic particles clog the drainage system. Treatment addresses both the underlying cause and the elevated pressure.

Although rare, glaucoma can affect infants and children. Congenital glaucoma results from an abnormally developed drainage system present at birth. Parents may notice excessive tearing, light sensitivity, or an enlarged, cloudy cornea in their child. Early surgical intervention is usually necessary to lower pressure and protect developing vision.

Glaucoma typically affects peripheral vision first. You may not notice missing areas because your brain fills in gaps using information from the other eye. Over time, the field of vision narrows, sometimes described as looking through a tunnel. Central vision is usually preserved until late in the disease, which is why many patients feel their eyesight is fine even when substantial damage has already occurred.

While you cannot change risk factors like age, genetics, or ethnicity, certain habits may support overall eye health. Regular aerobic exercise has been associated with modest reductions in eye pressure. Maintaining a healthy weight, managing conditions like diabetes and high blood pressure, protecting your eyes from injury, and avoiding prolonged corticosteroid use when possible are all prudent steps. None of these replace the need for professional screening, but they contribute to a comprehensive approach to eye health.

Not necessarily. Ocular hypertension means your eye pressure is above the average range, but it does not automatically mean the optic nerve is being damaged. Many people with elevated pressure never develop glaucoma. However, high pressure does increase your risk, so our team will monitor you more closely with regular OCT scans and visual field tests to watch for any early signs of nerve damage.

Without treatment, glaucoma progresses at varying rates depending on the type, the level of eye pressure, and individual factors. Open-angle glaucoma may take years to cause noticeable vision loss, while an acute angle-closure attack can damage the optic nerve within hours. In all cases, untreated glaucoma can eventually lead to permanent, total blindness in the affected eye. Early diagnosis and consistent treatment are the most reliable ways to preserve your vision.

Treatment focuses on lowering intraocular pressure to a level that slows or stops further optic nerve damage. Options include prescription eye drops, laser procedures such as selective laser trabeculoplasty (SLT), minimally invasive glaucoma surgery (MIGS), and traditional surgical procedures like trabeculectomy or tube shunt implantation. Our glaucoma specialists develop a personalized treatment plan based on the type and severity of your glaucoma, your overall health, and your lifestyle preferences.

If you have a first-degree relative with glaucoma, we typically recommend beginning comprehensive screening by your mid-30s rather than waiting until age 40. Annual or biannual exams allow us to establish a baseline for your optic nerve and track even subtle changes over time. The earlier we identify the disease, the more treatment options we have and the more vision we can help preserve.